# A ladder 25mts long reaches a window of a building 20mts above the ground the ground. Determine the distance of the foot of the ladder ?

Jun 21, 2018

15mts

#### Explanation:

This is a right triangle: the base is one side, the height up the house is the other and the length of the ladder is the hypotenuse, so you can use Pythagorean's theorem to solve it:

${a}^{2} + {b}^{2} = {c}^{2}$

You have $c$ the length of the ladder and one of the sides let's call it $b$.

${a}^{2} + {20}^{2} = {25}^{2}$

${a}^{2} + 400 = 625$

${a}^{2} = 225$

$\sqrt{{a}^{2}} = \sqrt{225}$

$a = 15$